binaries are problems in Debian when managing modules with binaries.
Solution is usually to rename binary in one of the modules
For humanfriendly, you would get humanfriendly in python2 package and humanfriendly3 in pythno3 for example, each with its own manpage.
Not very cool, as you need, in python3, to know that binary name is not the same.. :-(
or, as python3 will be the default in future, keep original name in python3 module and rename for python2....